Pair inside priority queue

Question

I am trying to store pairs in priority queue and I am using a compare function that compares second value of each pair.

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Answer 1

This is what priority_queue looks like:

template<
    class T,
    class Container = std::vector<T>, 
    class Compare = std::less<typename Container::value_type>
> class priority_queue;

In other words, CompareDist should be the third argument and the second argument should be the container (which has value_type), like the following:

priority_queue<pair<int,int>,vector<pair<int,int>>,CompareDist> pq;

Notice also, that priority_queue is what is called a "container adaptor". Another container is used as the underlying container and the priority_queue has special members functions for accessing it. Another example of a container adaptor would be std::stack.

Answer 2

priority_queue<pair<int,int>,vector<pair<int,int>>,CompareDist> pq;

you need to provide second argument for the inbuilt template of priority_queue.